1. Field of the Invention
The present invention relates to an image taking apparatus which includes an image pickup device and which forms a subject image on the image pickup device and produces image signals.
2. Description of the Related Art
Many image taking apparatuses include light-emitting sections which emit flash toward a subject in synchronization with image taking action. In such an image taking apparatus, when a radiation field of flash emitted from the light-emitting section is set to a short focus point (wide-angle), much light is emitted out of image taking angle of view corresponding to a telephoto angle in response to a zoom switch being operated to a long focus point (telephoto) and therefore, electric power is consumed in vain. Accordingly, many image taking apparatuses employ a technique in which the radiation field of flash can be changed in association with operation of the zoom switch (see Japanese Patent Application Laid-open (JP-A) No. 55-129326 for example). According to JP-A 55-129326, at least one of the arc tube and the reflector is moved forward and rearward in the optical axial direction in accordance with operation of the zoom switch, thereby obtaining a radiation field suitable for the image taking angle of view in accordance with the operation position of the zoom switch.
However, there still remains a problem that if the arc tube is of rod-like shape like the xenon tube, excessive light is emitted sideway of the arc tube, and electric power is consumed in vain correspondingly.
As described in a Japanese Patent Application Laid-open No. 2-291538, there is a technique in which side reflection means is provided adjacent to the rod-like arc tube, light emitted in vain is emitted into the image taking angle of view so that the electricity efficiency is enhanced, and the suitable radiation field is obtained.
There are also a technique in which to enhance the electricity efficiency in light emission of flash, the Fresnel lens disposed in front of the arc tube is moved forward or rearward, thereby obtaining a suitable radiation field (see Japanese Patent No. 3262779), and a technique in which a shape of the reflection plate disposed behind the arc tube is deformed to obtain a suitable radiation field (see Japanese Patent Application Laid-open No. 6-180469).
In any of the techniques disclosed in the patent documents 1 to 4, however, there is a problem that the precision is not sufficient.